1. Field of the Invention
The present invention generally relates to a method for achieving multiple beam radiation vertical orthogonal field coverage by means of multiple feed-in dish antenna; in particular, it relates to a method capable of creating multiple mutually vertical orthogonal radiation fields so that the generated energy radiation gains are all consistent thereby increasing the energy coverage of the electro-magnetic wave radiation environment and improving the transmission efficiency.
2. Description of Related Art
Because of rapid developments in mobile communication fields lately, multiple beam communication technology is now increasingly important, and in response to the imminent 5th generation mobile communication era, there seems to be a trend that the frequency bands utilized by antennas are moving toward high-frequency segments and the applications thereof are expected to extend into the range of millimeter waves (mmWave). For the millimeter wave frequency bands applied on satellite communications, the microwave wavelength and antenna structure thereof would become smaller, but significant losses are inevitable upon traveling in air, and in order to be adapted to the concept of multi-application and multi-channel, it is hoped the utilization of multiple beams can be effectively achieved. Meanwhile, for implementing high-gained antennas, conventionally it is done by means of phase array antennas, especially emphasizing on the use of PCB or LTCC manufacture processes for embodying relevant hardware, and such manufacture processes have been the mainstreams in prior art mobile communication technology developments. However, in case that the required frequency bands in schedule belong to the mmWave field, quite a few challenges may be encountered with regard to technical details and hardware implementations; especially, in terms of relevant hardware for realizing 5G high-gained antennas (or radio frequency (RF) related technologies), the embodiments of array antenna may exhibit a large amount of energy losses thus further undesirably generating noise interferences.
The aforementioned issues may become more uncontrollable for active components, including that the changes or variations in amplitudes and RF phases are comparatively unstable, which may vary in accordance with ambient temperature, the scale of noises or even different manufacture batches. Especially, the implementations of array antenna require cooperative feed RF circuits and the constitution thereof may employ massive active components, while this type of circuits potentially leads to relatively significant energy losses in millimeter waves. Consequently, to maintain the required antenna gain, the number of antenna units has to be increased; for example, in case the antenna circuit loss is 3 dB, the number of antenna units must be doubled thereby compensating the energy losses. Whereas, even the number of antenna units is doubled, the complexity in the RF feed circuits may further elevate, which results in more energy losses at the same time, so the actual number of antennas could become quite big. Moreover, the formation of beams in an array antenna needs phase variations from the phase shifter to attain the desired beam; but, in millimeter-wave frequency bands, active components and passive components all generate unstable phase differences, so the formation of the required beam could be pretty challenging.
Additionally, from another angle of view, in mobile communications, communication operations emphasize on the coverage of electro-magnetic waves. For the above-said 25 dBi antenna gain, under ideal conditions, we can first discuss the coverage issue in terms of so-called directivity, and the energy gain is equal to 100% at this point. However, in case of embodying such a 25 dB antenna directivity by means of an array antenna, the 3 dB beam width thereof would be approximately 9 degrees; suppose the antenna unit loses 3 dB due to the aforementioned reasons (i.e., 50% of energy losses), in order to compensate such losses, the number of antenna units needs to be doubled, thus the beam width may correspondingly become narrower, e.g., 5 degrees, which may greatly lessen the coverage range and significantly increase the complexity of the system. Besides, the energy losses in active circuits may further require more antenna units, thus further compressing the beam width and causing negative influences on the coverage.
Consequently, to overcome the above-said issues, it is possible to use the dish antenna and apply the multiple feed-in feature for implementing the multiple beam coverage function so as to enlarge the coverage range. In addition, to achieve the objective of multiple beam coverage, the antenna feed-in position needs to be deliberately moved away from the focusing point, i.e., to focus in an offset-focusing approach, so it is allowed to place several offset-focusing antennas to provide the multiple beam function. Moreover, through disc transformations, the focusing point of such an offset-focusing approach may be enlarged or transformed into a horizontal axis or vertical axis such that more antennas can be placed therein in order to implement the multiple beam antenna function. Therefore, using this type of offset-focusing dish antenna to achieve the goal of multiple beam coverage may resolve the issues described previously thereby providing an optimal solution.